Process of making iron-prints by photography



CHARLES R. MCBLAIR, OF \VASIIINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO MILTON IV. OFFUT", OF TOIVSONTOIVN, MARYLAND.

PROCESS OF MAKING IRON-PRINTS BY PHOTOGRAPHY.

SPECIFICATION forming part of Letters Patent No. 442,450, dated December 9, 1890.

Application filed May 12, 1890. $erial No. 351,530. (No specimensJ To aZ Z whom it may concern.-

Be it known that I, CHARLES R. )ICBLAIR, a citizen of the United States, and residing at Washington, in the District of Columbia, have invented certain new and useful Improvements in the Process of Making Iron-Prints by Photography 5 and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which itappertains to make and use the same.

My invention consists in the use of a solution hereinafter specified and in a process adapted, in connection with said solution, for the reproduction of d rawin and other works of art.

The object of my invention is to produce copies of drawings and other works of art which shall have dark and permanent lines upon a white background, said copy thus presenting to the eye the same, or substantially the same, appearance as that of the original.

To carry my invention into effect the paper or material upon which the copy is to be produced is preferably moistened with the following sensitizing solution, to wit: water, one pint; sesquichloride of iron, three ounces, and tartaric acid, half an ounce. The paper is moistened by the solution and then dried in any ordinary manner. In order to obtain acopy the sensitized paper is laid in an ordinary frame in contact with the positive to be copied, exposed to the sunlight for about ten or fifteen minutes, then removed and developed by passing it through a bath of gallic acid or its equivalent.

It is found that by using a thoroughly-calendered paper the use of gelatine or similar substance to hold the sensitizing solution is rendered unnecessary.

The above is the mode in which I preferably carry my invention in to effect; but it has been found that good results can be obtained by the addition of prosulphate of iron in the proportion of five-eighths of an ounce to the solution above specified.

I do not limit myself to the exact proportions hereinbeforc set forth nor to the precise materials mentioned, as I reserve the right to vary such proportions, and employ instead of the materials named others having equiva lent chemical properties.

'l'laving described my invention, I claim-- The method of sensitizing paper or similar material for the production of prints and pictures in dark lines by a solution of water, sesquichloride of iron, and tartaric acid, in or about the proportions hereinbefore set forth.

2. The method of sensitizing paperorsimilar material for the production of prints and pictures in dark lines directly from a positive by a solution of water, sesquichloride of iron, tartaric acid, and prosulphate of iron, in or about the proportions hereinbefore set forth.

The process of reproducing drawings, consisting in first sensitizing the material upon which the reproduction is to be taken with the following solution, to wit: water, sesquichloride of iron, and tartaric acid, or their chemical equivalents, mixed in substantially the proportions above specified, placing the sensitized material in contactwith the original, subjecting both to the action of solaror other strong light, and developing such reproduction by the use of gallic acid orits equivalent.

at. The process of reproducing drawings, consisting in first sensitizing the material upon which the reproduction is to be taken with the following solution, to wit: water, sesquichloride of iron, tartaric acid, and prosulphate of iron, or their chemical equivalents, mixed in substantially the proportions above specified, placing the sensitized material in contact with the original, subjecting both to the action of solar or other strong light, and developing such reproduction by the use of gallic acid or its equivalent.

In testimony whereof I have hereunto set my hand and seal this 12th day of May, 1890.

CHARLES R. MCBLAIR. [n s] Witnesses:

GEO. 1-1. HOWARD, PHILIP MONRO. 

